Eye diseases such as age-related macular degeneration or diabetes affect retinal pigment epithelium (RPE) function and lead to retinal degeneration, vision loss and blindness. To study RPE function, physiology and pathology many laboratories have attempted to culture RPE as a more accessible alternative to native tissue. This goal has been accomplished with varying degrees of success due to the functional and morphological complexity of the RPE and its neighboring cells in the retina and the choroid. We have developed techniques for culturing confluent monolayers of human fetal RPE cells that exhibit morphology, physiology, and patterns of protein expression similar to native human fetal RPE. One of the goals of this work was to identify a set of commercially available ingredients to create stable and reproducible RPE cell cultures. We been able to produce confluent pigmented RPE cell cultures with classic epithelial morphology, transepithelial potential of 1 - 3mV, and transepithelial resistance greater than 400 Oms*cm2. In the present experiments we further characterized these cultures using electron-microscopy and immunohistochemistry to identify cell structures, and localize apical and basolateral membrane and intercellular junctional complex proteins. ELISAs were used to confirm the polarity of secretion of selected cytokines. Intracellular microelectrodes were used to characterize receptor-mediated second messenger pathways and their downstream electrophysiological properties at the apical and basolateral membranes. The capacitance probe technique was used to measure net transepithelial fluid transport. This model has been used to help identify some of the mitochondrial pathways that mediate oxidative stress and the protective effects of lipoic acid.